As disclosed in U.S. Pat. Nos. 4,439,617 (Sestanj et al.), 4,592,866 (Cale), and 4,663,452 (Lilje), German Patent No. 741,109 (Dieterle), and Scheeren et al., Synthesis, 1973, pp. 149-151, it is known that carbonyl compounds can be converted to the corresponding thiono compounds by reaction with tetraphosphorus decasulfide (more commonly, though less accurately, known as phosphorus pentasulfide). Scheeren et al. teach that the reaction rates can be increased by conducting such thiations in the presence of sodium sulfide, carbonate, or bicarbonate and a polar solvent, Dieterle discloses the use of alkaline earth carbonates and oxides in such thiations to increase yields, and Lilje teaches that both the reaction rates and yields can be improved by conducting such thiations in the presence of an alkali metal bicarbonate and a hydrocarbon diluent.